Neutropenia is defined as a decrease in the blood neutrophil count below 1.5×10(9)/L. In some racial groups (eg Africans), the normal neutrophil count is somewhat lower (up to 1.2×10(9)/L). While mild neutropenia may be asymptomatic, severe neutropenia (counts< 0.5×10(9)/L) is invariably associated with the risk life-threatening microbial sepsis caused by a broad range of endogenous Gram-positive bacteria (S.aureus) and Gram-negative bacteria (E. coli, Pseudomonas spp, Klebsiella spp) as well as fungi (Candida). Neutrophils are particularly important for maintaining the integrity of mucous membranes. Hence, oral ulceration and perianal inflammationcan be features of severe neutropenia.